How can i change a bolt head to pan type?
If the menu for the options is not visible you can access a floating window with the same options it by pressing F6



If the menu is not visible on the tool panel, then press the + sign at the bottom of the panel.



Note that you can only set the parameters at the time of creation of the object.

Modifications have to be done before you use any other tool. Once you made any kind of transformation (scale, move, rotate, etc, or selected another object) there is no way to get the menu back. At that point, the only way to change the parameters is by creating a new object.